A waffle slab is a reinforced concrete floor or roof system designed with a flat top and a grid of deep, intersecting ribs underneath. Builders create these voids using square plastic or metal dome forms called pans before placing the concrete. This structural design significantly reduces the dead weight of the floor while maintaining the capacity to span long distances and carry heavy loads.
The prints call for a twelve-inch waffle slab in the main lobby, so we need to get the pan forms laid out and oiled by Tuesday.
The voids created by the pans are often left exposed for architectural effect, requiring excellent consolidation around the ribs to prevent honeycombing.
Also heard as
- Waffle slab
- Two-way joist slab
Related terms
Slab
A flat, horizontal expanse of cast concrete used as a floor, roof, or pavement.
Pan
A round steel float disc clipped onto a power trowel's blades for the first, flattening machine passes.
Formwork
The temporary molds, supports and bracing that hold fresh concrete in shape until it can carry itself.
Honeycomb
Patches of bare, loosely bound stone with open gaps, left where paste never worked in around the coarse rock.